1986 Trans Am 305 TPI stalling when put in gear (sometimes)
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1986 Trans Am 305 TPI stalling when put in gear (sometimes)
Hi-
I have a completely stock 1986 Trans Am with the 305 TPI and 700r4 transmission. It runs and drives very well with the exception of one pretty predictable idle related issue. The issue described below will only happen with an already fully warmed up engine that has been driven then parked for just enough time to cool down a bit ( usually 20-30 minutes ). Upon restarting the car the idle will flutter a bit lower then usual (around 500-600 in park) and when putting the trans into forward or reverse gear the rpms will drop almost stalling the engine or most often will stall quickly. During this situation, if I rev the engine up it often will stall as the RPMs drop back down. I found simply "two feeting" the gas and brake pedal works well to get me in gear and going. After a short drive and engine temp up a bit more, the idle will be healthy again and I can go in out of gear without issue. Normally the idle is smooth and steady at cold start, during warm up, and when warm and when restarted warm. Going in and out of gear is also no issue during these points. Again the issue only begins to occur when an already warm engine is parked and allowed time to cool off a bit. Seems to me like the issue is predictable and possibly temperature related and that the computer just decides to stop controlling the idle for that lukewarm timeframe after a partial cool down.
My TPS is set to .54 Volts. Normal idle in park is about 800. No check engine codes. 195 Thermostat. Any advice would be appreciated.
I have a completely stock 1986 Trans Am with the 305 TPI and 700r4 transmission. It runs and drives very well with the exception of one pretty predictable idle related issue. The issue described below will only happen with an already fully warmed up engine that has been driven then parked for just enough time to cool down a bit ( usually 20-30 minutes ). Upon restarting the car the idle will flutter a bit lower then usual (around 500-600 in park) and when putting the trans into forward or reverse gear the rpms will drop almost stalling the engine or most often will stall quickly. During this situation, if I rev the engine up it often will stall as the RPMs drop back down. I found simply "two feeting" the gas and brake pedal works well to get me in gear and going. After a short drive and engine temp up a bit more, the idle will be healthy again and I can go in out of gear without issue. Normally the idle is smooth and steady at cold start, during warm up, and when warm and when restarted warm. Going in and out of gear is also no issue during these points. Again the issue only begins to occur when an already warm engine is parked and allowed time to cool off a bit. Seems to me like the issue is predictable and possibly temperature related and that the computer just decides to stop controlling the idle for that lukewarm timeframe after a partial cool down.
My TPS is set to .54 Volts. Normal idle in park is about 800. No check engine codes. 195 Thermostat. Any advice would be appreciated.
Last edited by kingbowl93; Mar 15, 2021 at 02:20 PM.
Junior Member
Joined: Mar 2019
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From: PA
Car: 91'Z 89' RS 68'
Re: 1986 Trans Am 305 TPI stalling when put in gear (sometimes)
Hi-
I have a completely stock 1986 Trans Am with the 305 TPI and 700r4 transmission. It runs and drives very well with the exception of one pretty predictable idle related issue. The issue described below will only happen with an already fully warmed up engine that has been driven then parked for just enough time to cool down a bit ( usually 20-30 minutes ). Upon restarting the car the idle will flutter a bit lower then usual (around 500-600 in park) and when putting the trans into forward or reverse gear the rpms will drop almost stalling the engine or most often will stall quickly. During this situation, if I rev the engine up it often will stall as the RPMs drop back down. I found simply "two feeting" the gas and brake pedal works well to get me in gear and going. After a short drive and engine temp up a bit more, the idle will be healthy again and I can go in out of gear without issue. Normally the idle is smooth and steady at cold start, during warm up, and when warm and when restarted warm. Going in and out of gear is also no issue during these points. Again the issue only begins to occur when an already warm engine is parked and allowed time to cool off a bit. Seems to me like the issue is predictable and possibly temperature related and that the computer just decides to stop controlling the idle for that lukewarm timeframe after a partial cool down.
My TPS is set to .54 Volts. Normal idle in park is about 800. No check engine codes. 195 Thermostat. Any advice would be appreciated.
I have a completely stock 1986 Trans Am with the 305 TPI and 700r4 transmission. It runs and drives very well with the exception of one pretty predictable idle related issue. The issue described below will only happen with an already fully warmed up engine that has been driven then parked for just enough time to cool down a bit ( usually 20-30 minutes ). Upon restarting the car the idle will flutter a bit lower then usual (around 500-600 in park) and when putting the trans into forward or reverse gear the rpms will drop almost stalling the engine or most often will stall quickly. During this situation, if I rev the engine up it often will stall as the RPMs drop back down. I found simply "two feeting" the gas and brake pedal works well to get me in gear and going. After a short drive and engine temp up a bit more, the idle will be healthy again and I can go in out of gear without issue. Normally the idle is smooth and steady at cold start, during warm up, and when warm and when restarted warm. Going in and out of gear is also no issue during these points. Again the issue only begins to occur when an already warm engine is parked and allowed time to cool off a bit. Seems to me like the issue is predictable and possibly temperature related and that the computer just decides to stop controlling the idle for that lukewarm timeframe after a partial cool down.
My TPS is set to .54 Volts. Normal idle in park is about 800. No check engine codes. 195 Thermostat. Any advice would be appreciated.
Member
Joined: Jun 2020
Posts: 189
Likes: 98
From: Western Pa
Car: 1989 Trans Am
Engine: 305 H.O. TPI
Transmission: Auto 700R4
Axle/Gears: 3.42 posi
Re: 1986 Trans Am 305 TPI stalling when put in gear (sometimes)
This sounds exactly like an issue a guy on Youtube was having with a 91 TPI Formula, ended up being in the distributor, probably ICM but he replaced the entire distributor and problem solved, he went through the usual trouble shooting first, TPS, IAC, cleaning throttle body, etc. Would die when putting it in gear, had to two foot it. There were times he thought it was fixed by doing the normal stuff but it would just start dying with low erratic idle sometimes.
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